Thomas Townsend Brown discovered another effect which may be related to the electrogravitic effects observed upon condensers at high voltage. He noted that certain dielectrics, and most notably certain types of igneous rocks, exhibited a weak electrical potential. Through testing, he discerned that this is was neither piezoelectric (pressure induced voltage), or pyroelectric (heat-change induced voltage), but petrovoltaic. This is to say that there was a continuous, steady voltage across the rock, which changed very slowly, according to the lunar cycle, positions of stars, position of the sun, and such like.

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Brown spent time in the seventies on Hawaii, testing what he called his "geophysical sensors". These were foot-long cores of Hawaiian "Koolau Basalt" which had electrodes painted on, and then were electrically isolated. There were placed at various locations on the islands to locate regional differences in the noted effect. In my replication, I have been lucky enough to procure some of the same type of rock, though likely not identical, from Rick Monteverde, to whom credit for this experiment must go. The phases intended for this project are as follows:

Establish the existence of such an effect

Isolate this from the influences of pressure and heat and other interference

Determine best materials for this effect, and determine if it can be put to useful work

The first and second sections are all that I have attempted so far, and have only been able to draw preliminary conclusions......

I received my rocks from Hawaii, and was informed that they had been boiled to kill off any parasites therein. This is good for customs and excise, but also because it removes any surface residues. I received one large slice of a core, about three inches in diameter, and a quarter inch thick. I also received some loose rocks:

The rock collection

To begin with, the experimental setup was very simple, I only wished to determine whether or not there was indeed a voltage across the rocks, without a load or any other kind of circuit - just the rock. I used a small multimeter to record my findings, sensitive down to one millivolt. The meter is a Hilka 90030013 High Safety DMM.

My multimeter

To test, I spread a small amount of hydrogel (pH 7) on each face of the rock to be tested, and connected the voltmeter across it. I was very careful to position the rock so that there was no possible compression of it by my pushing the electrodes. The electrodes did not touch the rock, but were inserted into the hydrogel blobs on either face of the rock. The results were mixed............

From what I could see, the results observed seemed to be a combination of the piezoelectric effect, and another effect, which mught possibly be the petroelectric. At first, I had simply held the electrodes to the rocks with my hands, and though the metal tips of the probes never touched the rocks directly (they were in the hydrogel blobs), there might have been minute pressure changes. Usually, each of the small rocks delivered a voltage of 30-50 millivolts upon first contact, which then slowly tailed off. This is to be expected from a piezo effect, but not all of the rocks totally levelled off to nothing. Two or three of them levelled at around 12 millivolts, then remained there, even after twelve hours had elapsed.

The core slice seemed to be "dead", though I did not try all possible connections. The most crucial failure of this test it that I could not generate the super-resistances which Brown used - I was simply measuring the free-floating potential of the rock. Despite this, when I hooked up the rocks to the meter with tape to hold the electrodes in place so there could be no change in pressure - thus ruling out piezoelectricity, the small voltage remained. Some of the rocks still remained dead, whereas some continued to produce the tiny voltages noted above.

For all this, and having more or less ruled out piezoelectric effects, I still cannot rule out a chemical reaction or some kind of thermal effect. As Rick Monteverde said, the results proved inconclusive. All I am capable of saying is that certain types and shapes of rocks produce a small measurable voltage which is independent of the pressure on the rock.